Funds are requested for assistance with the purchase of a 600 MHz high-resolution NMR spectrometer, equipped with a high-sensitivity cryogenic probe. The instrument will serve the needs of five major and two minor user groups performing a wide variety of research projects in structural aspects of biochemistry at Indiana University, Bloomington, IN. We currently have just 50% of the time on a single 500 MHz NMR spectrometer allocated for biomolecular NMR work. In this proposal we outline an urgent need for more biomolecular NMR time. Several of the systems we are studying involve large proteins or complexes, intermediate exchange behavior, low temperatures, or compounds with poorly resolved spectra. In all of these situations, the relatively high resolution of the requested instrument will enhance our ability to interpret the spectra. In addition, a number of the proposed projects involve samples that are sparingly soluble, available in very small quantities, or with weak intrinsic signals due to broad lines. In these cases the very high sensitivity of the cryogenic probe will be crucial for obtaining adequate spectra. The requested instrument will be administered by the Chemistry Department's NMR Facility. There is strong institutional support for this acquisition from Indiana University.